Calculate the center

Property definitions

geometry $ PolygonSorter :: calc_center
	# Calculate the center
	fun calc_center(pts : Array[Array[Float]]): COMPARED do
		var sumx = 0.0
		var sumy = 0.0
		for ap in pts do
			sumx += ap[0]
			sumy += ap[1]
		end
		return new Point[Float](sumx / pts.length.to_f, sumy / pts.length.to_f)
	end
lib/geometry/polygon.nit:322,2--331,4